1. Field of the Invention
This invention relates to a construction machine for working pieces of ground, having a milling roller on which surface chisel holders are arranged, wherein a chisel, in particular a round shaft chisel, is exchangeably received in a chisel receiver of the chisel holder.
2. Discussion of Related Art
A construction machine designed as a road-milling machine is taught by German Patent Reference DE 39 03 482 A1. Road coverings can be cut off by road-milling machines. The chisels continuously wear out during operation of the machine. After the chisels have reached a certain wear state, they must be replaced. Thus it is necessary for a worker to approach the milling roller and there drive the chisels out of the chisel holders. For driving the chisels out, the worker uses a special ejection mandrel and a hammer. This can lead to injuries. Manipulation in the narrow milling roller area is extremely difficult and requires great care in order to reduce the risk of danger. After a chisel is removed from its chisel holder, it is necessary to insert fresh unworn chisels into the chisel holders. Replacement of the chisels is a very arduous and time-consuming job.
Manually operable exchangeable tools are known from German Patent Reference DE 32 23 761 C2 and from U.S. Pat. No. 3,342,531. They have a shoulder, which positively engages a circumferential groove in the chisel. The chisels can then be levered out of the associated chisel holder. Although the exchange process is easier with this, working on the milling roller is nevertheless dangerous and arduous.